The candidate's long-term goal is to develop interventions that support women who require immunosuppressive therapy during their childbearing years to achieve optimal health. The immediate goal is to describe and compare the quantity of immune factors and prolactin present in colostrum from those mothers' treated with immunosuppresive agents and those mother's who are not. To achieve these goals, a focused research career development plan is proposed, including intensive study of: (1) lymphocytes, cytokines and immunoglobulins in relation to colostrum and breast milk, (2) immunsuppression in women during lactation, (3) and longiturdinal design. Increasingly, women after organ transplants and/or with autoimmune diseases who are treated with immunosuppressive drugs become pregnant and interested in breast-feeding. Over 50% of infants born to cyclosporine and tacrolimus treated mothers are low birth weight (LBW) and preterm compared to 5% in the general population. The benefits of administering colostrum to this high-risk infant population are substantial. However, since cyclosporine and tacrolimus is excreted in breast milk, breast-feeding is not recommended, despite current studies that report infants do not absorb detectable amounts of cyclosporine. No studies have described the effects of cyclosponne or tacrolimus on the immune factors of colostrum that are so valued for the infant. The purpose of the proposed study is to investigate the effects of cyclosporine and tacrolimus on specific immune factors found in breast milk (IL-1b, IL-4, IL-10, IgA, IgE, IgG, and IgM) and prolactin that are known to have a direct relationship with cyclosporine and tacrolimus in the adult systemic immune system. Specific aims include measuring immune factors, prolactin and levels of cyclosporine and tacrolimus in colostrum on days 1 and 3, post partum. Mothers will be 18 to 45 yrs of age and approximately 20 treatment-subjects and 20 control-subjects will be recruited and matched according to post partum duration. We will measure immune factors and protactin by method of ELISA. Tacrolimus and cyclosporine will be quantified using HPLC method and lymphocytes utilizing flow cytometry. Data analysis will include descriptive statistics, Students' t-test to make comparisons and Pearson's Product moment for correlations.